DOCTYPE error in FireBug

hello, how you solved that error I am having the same problem
help me please

The Firebug error you see is a result of an empty src attribute on the script element caused by the plugin overriding WordPress script loader with a asynchronous loading script block.
https://core.trac.www.ads-software.com/ticket/22470

Thanks for the update, Niall. It’s not a critical issue since browsers still render the site but it’d be nice to have clean validation. I’d prefer it if the issue stayed unresolved until WP accepts your patch but I’m not too fussed. Main thing for me is knowing that it’s expected behavior.

db

The empty script src issue is fixed in the next version of WordPress.
https://core.trac.www.ads-software.com/changeset/25465